Press Releases: Northern California
October 31, 2006
Too Much Weight Gain During Pregnancy May Be Associated With Complications for Newborns
OAKLAND, Calif. – Pregnancy weight gain above the Institute of Medicine (IOM) guidelines is associated with an increased risk of complications in newborns, according to researchers from Kaiser Permanente’s Division of Research in Oakland, CA.
Women who gained more weight than recommended by the IOM were three times more likely than women whose weight gain was in the recommended range to have an infant with higher than normal birth weight and nearly 50 percent more likely to have an infant with jaundice or lower than normal blood sugar. Conversely, women who gained too little weight were less likely to have an infant with higher than normal birth weight and had no altered risk of the other two complications studied.
“This study tells us that normal weight gain for mothers during pregnancy may have an important impact on the health of their newborns,” said Monique M. Hedderson, PhD, the lead author of the study published in the current issue of Obstetrics & Gynecology. She explained that there has been an increase in the number of women entering pregnancy overweight or obese and in the percentage of women experiencing excessive weight gain during pregnancy.
“There are a lot of myths that need to be overcome with education,” added Hedderson. She noted that myths include the notion that pregnant women need to eat for two and take what is known as a “pregnant pause” from healthy activity.
Randomized trials designed to test interventions to help women achieve the recommended weight gain are needed, according to Assiamira Ferrara, MD, PhD, a co-author on the study. IOM recommendations for weight gain vary by pre-pregnancy body size: underweight women should gain between 28 and 40 pounds, normal weight women should gain between 25 and 35 pounds, overweight women should gain between 15 and 25 pounds, and obese women should gain at least 15 pounds.
In this study, 80 percent of mothers who had higher than normal birth weight infants gained more than recommended by the 1990 IOM guidelines. Similarly, 61 percent of mothers who had infants with low blood sugar and 59 percent of women who had infants with jaundice had gained more weight than recommended by IOM.
The researchers suggest that over-nutrition may lead to the infant having excess insulin, which may cause excess growth of fat tissues. It is also possible that infant overproduction of insulin leads to overproduction of red blood cells that can result in jaundice or reduces mobilization of glycogen (a large molecule that stores sugar) from the liver to the blood, resulting in infant low blood sugar.
In addition to these problems, higher than normal birth weight predisposes the mother to needing a C-section and the infant to obesity later in life. Severe jaundice and severe low blood sugar may result in brain damage and /or have an impact on cognitive function during childhood, they explained.
From a cohort of 45,245 women who delivered single babies between 1996 and 1998 and who did not have gestational diabetes between weeks 24 and 28, researchers selected a random sample of 400 infants with each complication. They compared their mother’s weight gain during pregnancy to mothers of 650 infants without these complications. They examined neonatal complications in relation to: 1) total pregnancy weight gain according to IOM recommendations, 2) rate of maternal pregnancy weight gain (total pregnancy weight gain minus infant birth weight divided by weeks of gestation), 3) and rate of pregnancy weight gain before the third trimester. The researchers adjusted for maternal age, race or ethnicity, parity, 1-hour screening glucose value, and the difference between gestational age at delivery and at the time the last weight was measured.
Other researchers involved in this study include Noel S. Weiss, MD, DrPH, University of Washington; David A. Sacks, MD, Kaiser Foundation Hospital, Bellflower, CA; David J. Pettitt, MD, Sansum Diabetes Research Institute, Santa Barbara, CA; and Joe Selby, MD, MPH, Charles P. Quesenberry, PhD, and Assiamira Ferrara, MD, PhD, all with the Kaiser Permanente Division of Research.
The research was supported by the National Institute of Diabetes and Digestive and Kidney Diseases, a grant from the American Diabetes Association, and Kaiser Community Benefit research support to Dr. Ferrara.
The Kaiser Permanente Division of Research conducts, publishes, and disseminates epidemiologic and health services research to improve the health and medical care of Kaiser Permanente members and the society at large. It seeks to understand the determinants of illness and well-being and to improve the quality and cost-effectiveness of health care. Currently, DOR’s 400-plus staff is working on more than 250 epidemiological and health services research projects.
For more information on Kaiser Permanente Research, go to: News Center's Health Research section.
